Idle roll mill



K. SAXL IDLE ROLL MILL June 30, 1964 Filed June 29. 1961 United States Patent 3,138,980 IDLE ROLL MILL KarelSaxl, Sutton Coldfield, England, assignor to Imperial Chemical Industries Limited, London, England,

a corporation of Great Britain Filed June 29, 1961, Ser. No. 120,753 Claims priority, application Great Britain July 7, 1960 8 Claims. (Cl. 80-40) This invention is concerned With apparatus for reducing the thickness of metal in strip or slab form.

In patentees prior application numbered 784,524 and 840,130, the former now U.S. Patent 3,103,139, there are described methods and apparatus for reducing the thickness of metal in which the metal is passed between a pair of freely-rotatable Work rolls which are oscillated in synchronism in pendulum-like manner in arcuate paths on opposite surfaces of the metal. The rolls oscillate at high speeds and metal is reduced in increments while passing through a short deformation zone.

While large reductions in thickness were achieved in a single pass by the methods disclosed in the said specifications, the surfaces of the reduced metal were somewhat undulatory. It has been found that the surface of the metal may be improved by modifications in the methods referred to.

According to the invention there is provided apparatus comprising a pair of opposed swingable arms, the free ends of which are adjacent, a freely-rotatable work roll mounted on the free end of each arm, mechanical driving means operable so as to cause swinging of the arms forward and backward in synchronism with each other, resilient means permitting displacement of the pivots of swingable arms in a vertical plane characterised in that disc-shaped members in the form of flanges or loose collars are arranged to operate between the free ends of the swingable arms at a point of minimum separation of the work rolls during movement of the swingable arms.

The preferred disc-shaped members are in the form of flanges at both ends of one or both Work rolls since the flanges also serve to produce good edges on the reduced metal. Where flanges are provided on both work rolls, the height of such flanges is one half of the thickness of the reduced metal.

In the apparatus of the invention, the freely-rotatable work rolls are provided with flanges having a height equivalent to half the thickness of the reduced metal and the mill is provided with resilient means between the pivots of the swingable arms on which the work rolls are mounted and the mill frame as described in the aforementioned specifications. During oscillation the axes of the rolls move in an arcuate path from their point of greatest separation and converge on each other. The distance between the pivots is such that eventually the flanges make contact and the rolls are diverted from their arcuate paths and move along parallel paths to the end of the stroke. Whilst the flanges are in contact, the rolling load is exceeded and the resulting compression of the resilient devices allows vertical displacement of the pivots and permits the swingable arms to continue their movement. When the direction of movement of the rolls is reversed, the paths of the roll axes are first parallel and then arcuate and divergent. The amount of vertical displacement by the pivots is small since the swingable arms are nearly at the end of their movement when the flanges make contact.

The length of the parallel portion of the roll paths need only be short relative to the total length of the paths but should be greater than the distance travelled during a cycle of two consecutive backward and forward swings 3,138,980 Patented June 30, 1964 ICE of the arms by the metal being reduced in order that undulations in the surface may be levelled out.

Rotation is imparted to the work rolls solely by contact between the rolls and the work-piece, i.e., the rolls are freely-rotatable, thereby avoiding slipping which is detrimental to the surface of the metal and is characteristic of independently driven rolls. Where backing rolls are used, these too are freely-rotatable.

The metal being reduced is fed through the rolls in a conventional manner and preferably by means of pinch rolls operating on the slab, but also on the reduced metal or a combination of both.

When pairs of pinch rolls are available for operating on both the unreduced slab and the strip it is ensured that the feed of the metal is always under control. Thus, while the unreduced portion of the slab is long enough to be engaged by the pinch rolls on the ingoing side of the mill, the metal is pushed through and when the end of the slab approaches the rolls, the strip is engaged by the pinch rolls on the outgoing side of the mill and is pulled through the mill. Both sets of pinch rolls may operate together. The feed of metal may be continuous or intermittent.

One embodiment of the invention will be described by way of the example with reference to the accompanying drawing which shows diagrammatically the method of reducing metal slab to strip.

Referring to the drawing, a pair of flanged work rolls 1 are mounted on swingable arms 2 which are pivoted on pivots 3. The pivots 3 are secured to the mill frame 4 by means of resilient devices 5 which may be in the form of strong coiled springs associated with the screwdown gear. Connecting rods 6 attached to the arms 2 and to driven cranks or eccentrics 7 cause the arms 2 to oscillate and the work rolls 1 to move along the paths 8. Movement is imparted to the slab 9 by a pair of pinch rolls 10 on the ingoing side of the mill and, if required, to the strip 11 by a pair of pinch rolls 12 on the outgoing side of the mill.

In operation, the slab 9 is advanced from right to left of the drawing by the pinch rolls 10 whilst the work rolls 1 are being oscillated and is incrementally reduced to strip by the repeated rolling action of the work rolls 1. When the work rolls 1 are in their furthest position from that shown in the drawing, the separation is greatest and movement of the work rolls 1 towards the outgoing side of the mill causes the Work rolls 1 to converge until the flanges meet at a point 13 on the path 8. From the point 13 until the work rolls I reach the position shown in the drawing, the paths of the work rolls 1 are parallel, the resilient devices 5 being compressed to permit' such movement of the pivots in a vertical plane.

In another embodiment of the invention the paths of the rolls are diverted from arcuate form by rotating spacing devices such as loose collars on one or both Work rolls or by freely-rotatable discs on vertical axes which engage with the working surfaces of the rolls during oscillation and so determine the minimum separation.

I claim:

1. Apparatus reducing the thickness of metal comprising: a pair of freely rotatable work rolls operative to receive a strip of metal advanced therebetween; and means for moving said work rolls in synchronism through paths which have a forward stroke which is first arcuate and then substantially parallel to one another and then through a backward stroke which is the reverse of said forward stroke, said means also operative to keep said rolls in contact with the metal strip during said strokes, whereby the metal is subjected to a smoothing action after being deformed.

2. Apparatus defined in claim 1 wherein said Work rolls are connected to the free ends of opposed swingable arms, the free ends of which are adjacent.

3. Apparatus defined in claim 2 wherein said resilient means are compression springs.

4. Apparatus defined in claim 2 wherein said moving means includes: mechanical drive means operative to oscillate said arms; resilient means providing displacement of the opposite pivotal ends of said arms in a plane generally perpendicular to the path of movement of the meta1 strip between said work rolls; and disc-shaped members constructed and arranged to operate between the free ends of said arms at a point of minimum separation of said work rolls.

5. Apparatus defined in claim 4 wherein each of said disc-shaped members are co-axial with and located at each end of said work rolls, each of said disc-shaped members having a radius greater than the radius of each of said work rolls by an amount equal to one-half the thickness of said strip, said disc-shaped members on one of said work rolls being located to make pivot-displacing contact with the said disc-shaped members on the other of said work rolls during said swinging movement.

6. Apparatus defined in claim 5 wherein said discshaped members are integral with said work rolls.

7. Apparatus defined in claim 5 wherein said discshaped members are independently rotatable relative to said work rolls.

8. Apparatus for reducing the thickness of metals comprising: at least one freely rotatable work roll and a surface positioned in opposed relationship to said work roll to receive a metal strip advanced therebetween; and means for swinging said work roll through forward and backward strokes wherein said work roll is maintained in continuous contact with said metal strip, said forward stroke having a path which is first arcuate and then generally parallel to the path of movement of said metal strip on said surface, said backward stroke being the reverse of said forward stroke, whereby the metal is urged to a smoothing action after being deformed.

References Cited in the file of this patent UNITED STATES PATENTS 995,427 Inshaw June 12, 1911 2,153,839 Liebergeld Apr. 11, 1939 FOREIGN PATENTS 332,084 France Oct. 15, 1903 1,212,644 France Oct. 19, 1959 704,757 Germany Apr. 5, 1941 787,442 Great Britain Dec. 11, 1957 

1. APPARATUS REDUCING THE THICKNESS OF METAL COMPRISING: A PAIR OF FREELY ROTATABLE WORK ROLLS OPERATIVE TO RECEIVE A STRIP OF METAL ADVANCED THEREBETWEEN; AND MEANS FOR MOVING SAID WORK ROLLS IN SYNCHRONISM THROUGH PATHS WHICH HAVE A FORWARD STROKE WHICH IS FIRST ARCUATE AND THEN SUBSTANTIALLY PARALLEL TO ONE ANOTHER AND THEN THROUGH A BACKWARD STROKE WHICH IS THE REVERSE OF SAID FORWARD STROKE, SAID MEANS ALSO OPERATIVE TO KEEP SAID ROLLS IN CONTACT WITH THE METAL STRIP DURING SAID STROKES, WHEREBY THE METAL IS SUBJECTED TO A SMOOTHING ACTION AFTER BEING DEFORMED. 